Rob,
Domino pretty much nailed it on the VG description. Actually, my first 6 months of vaping (mostly with an 801) I only used VG based liquid. Then they changed their recipe and I couldn't stand the taste of their liquid any longer.
Sometimes, I do add a little VG to the PG liquid I get from you. Not always though. I usually mix 2 (and sometimes 3 flavors) in a 30ml bottle. And depending on my mood, I will sometimes add some VG to it. I rarely vape a liquid "as is"........almost always am mixing flavors to create unique stuff.
But a thick liquid does not work well in the cartos. I think most VG based liquid is mixed with distilled water to thin it.